Answer: The electrician wrapped the wires with plastic caps because plastic is an insulator.
Explanation: Metals are excellent conductors of electricity, largely because electrons in the metal are only loosely bound by their respective atoms and thus will readily flow under the influence of an external electric field. Plastics are very different. All the electrons in plastics are tightly bound by their respective molecules and it would take a lot of energy to remove them. Consequently, most plastics are insulators that do not conduct electric current (or do so only poorly).
Answer:
The electrical wires are made of metal, which conducts electricity. In order to make the wiring safe, he would wrap the exposed wire with plastic materials, which are good insulators. This keeps the flow of electricity contained to the light fixture and wiring.
